Characterization, Speciation, and Source Apportionment of Particles inside and from the Exhaust of Public Transit Buses Fueled With Alternative Fuels.

摘要

The practical issue of Scanning Electron Microscope/Energy Dispersive X-ray Spectrometry (SEM/EDX) instrumentation compatibility for particle analysis is addressed. The physical and chemical characterization of fine particles is carried out inside a public transit bus fueled with biodiesel (BD) and ultra low sulfur diesel (ULSD). The three sorts of square surface patterns represented the morphological characteristics of single inhalable particles in the air inside the bus in Toledo. The size and shape distribution results are compared to those obtained for a bus using ULSD and BD respectively.;Only the reproducible results from repeated experiments on ESEM and size distribution obtained by the GRIMM dust monitor are used in this study. The collected filters are analyzed using a computer controlled SEM to obtain aerosol elemental compositions. Factor analysis suggested possible sources of indoor particle levels in public transit bus as motor vehicles, outdoor soil and secondary particle formation. The conclusion is that SEM methodology is a valuable tool for studying the distribution of particulates.;A part of this study examines the toxic nature of these engine exhausts under different idling conditions. The results of the PM emission analysis showed that the PM mean value of emission is dependent on the engine operation conditions and fuel type. It is found that lubricant oil, PM ash content, and storage tanks are the major sources of elemental concentrations in the PM.;Another part of this study looks at the change from ULSD to BD in different idling mode that is investigated with respect to organic carbon (OC) and elemental carbon (EC) for public transit buses in Toledo, Ohio. The carbon source profile for both alternative fuels for eight carbon fractions is developed through real time experiments. The results indicated that the use of BD instead of ULSD is environmentally sustainable for human health and climate change.;A new method for determining kinetic parameters of soot oxidation is applied for exhaust particles collected from public transit buses. The results indicate that the use of BD in public transit buses will result in lower particle formation from the engine. Particle morphology is clearly spherical carbon nano particles with chain-like agglomerates.